Identification

From WikipediaAdult common gulls are 4046 cm long, noticeably smaller than the herring gull, and slightly smaller than the ring-billed gull, also differing from the latter in its shorter, more tapered bill with a more greenish shade of yellow, as well as being unmarked during the breeding season. The body is grey above and white below. The legs are greenish-yellow. In winter, the head is streaked grey, and the bill often has a poorly defined blackish band near the tip (sometimes sufficiently obvious to cause confusion with ring-billed gull). They have black wingtips with large white "mirrors". Young birds have scaly black-brown upperparts and a neat wing pattern, and grey legs. They take two to three years to reach maturity. The call is a high-pitched "laughing" cry

Both common and mew gulls (subspecies) breed colonially near water or in marshes, making a lined nest on the ground or in a small tree; colony size varies from 2 to 320 or even more pairs. Usually three eggs are laid (sometimes just one or two); they hatch after 2426 days, with the chicks fledging after a further 3035 days. Like most gulls, they are omnivores and will scavenge as well as hunt small prey. The global population is estimated to be about one million pairs; they are most numerous in Europe, with over half (possibly as much as 80-90%) of the world population. By contrast, the Alaskan population is only about 10,000 pairs.

Recommended books

Klaus Malling Olsen and Hans Larsson Another ground-breaking title in the highly acclaimed Helm Identification Guide series. Gulls of Europe, Asia and North America looks at this popular family in great detail. The book covers almost all of the world's species, and includes some of our most familiar seabirds as well as many little-known and globally threatened species. This group is notorious for posing immense identification problems, and all of the difficult intermediate plumages are described and illustrated with particular care. This guide, like the others in the series, combines comprehensive text with beautiful and accurate illustrations, and many colour photographs. Confusing species are covered in particular detail. The very latest information on habitat, range, movement and breeding behaviour is accompanied by appropriate maps and many explanatory line drawings. The book is from the same team who produced Terns of Europe and North America and Skuas and Jaegers, both published by Christopher Helm/Pica Press.